Wireless Communication Apparatus, Wireless Communication System, Wireless Communication Method and Program

ABSTRACT

A wireless communication apparatus is provided that performs wireless communication using a specified wireless channel and forms part of an ad hoc wireless network. The device includes a recording portion that records country ID information and recording-time information in to a storage medium, where the recording-time information indicates the time at which the country ID information was recorded in to the storage medium, a time determination portion that uses the recording-time information to determine whether a predetermined time period has elapsed from the time at which the country ID information was recorded, and a channel setting portion that, when the predetermined time period has not elapsed from the time at which the country ID information was recorded in the storage medium, sets a wireless channel to a frequency channel that can be used in the country indicated by the country ID information recorded in the storage medium.

CROSS REFERENCES TO RELATED APPLICATION(S)

The present invention contains subject matter related to Japanese PatentApplication JP 2007-058707 filed in the Japan Patent Office on Mar. 8,2007, the entire contents of which being incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a wireless communication apparatus, a wirelesscommunication system, a wireless communication method and a program.

2. Description of the Related Art

The WiMedia Alliance has developed the Distributed Media Access Controlfor Wireless Network and the Multi-band OFDM Physical LayerSpecification as access control standards for ultra wide band (UWB)wireless communication. These specifications describe a method for usewith wireless communication apparatuses forming a Multi-band OFDMwireless communication system. In this method, UWB wirelesscommunication is performed by hopping multiple frequency bandwidths in aspecific pattern.

In recent years, UWB wireless communications are being approved in moreand more countries around the world, while legal systems in each countrydiffer and the frequency bandwidths approved for use in Japan, Europe,Asia and other regions also differ. Also, specific countries have timelimit measures in place that approve the use of certain frequencybandwidths for a limited period of time. It is therefore necessary forwireless communication apparatuses to use the frequency bandwidths(wireless channels) that are approved by the country in which thewireless communication apparatus is located.

An example of a technology related to the current situation, namely, acommunication system that operates in accordance with the position of acellular telephone, is disclosed, for example, in Japanese PatentApplication Publication No. JP-A-2003-318802. To explain in more detail,in JP-A-2003-318802, a communication system is disclosed in which acellular telephone obtains location information from a cellulartelephone base station, and operates based on the circuit informationand a program that can be used in that location, as indicated by theobtained location information.

SUMMARY OF THE INVENTION

However, an ad hoc network operates without using a signal from acommunications equipment that corresponds to a base station forming partof a typical communications system, and so it is not possible to acquireinformation from the communications equipment corresponding to the basestation relating to the position of a wireless communication apparatusforming part of an ad hoc network. Also, a wireless communicationapparatus is sometimes carried to a different country by a user.Therefore, even if country ID information is set once for the country inwhich the wireless communication apparatus is located, the reliabilityof the country ID information cannot be maintained with the passing oftime.

The present invention addresses the above-identified problems andprovides a new and improved wireless communication apparatus that canset a wireless channel based on highly reliable country ID information,a wireless communication system, a wireless communication method and aprogram for use in an ad hoc network.

According to an embodiment of the present invention, there is provided awireless communication apparatus that performs wireless communicationusing a specified wireless channel and that forms part of an ad hocnetwork. The wireless communication apparatus includes a recordingportion that records country ID information indicating a country on theearth in to a storage medium, and that further records in to the storagemedium recording-time information indicating the time at which thecountry ID information is recorded in to the storage medium, a timedetermination portion that, at the start-up of the wirelesscommunication apparatus, uses the recording-time information todetermine whether or not a predetermined time period has elapsed fromthe time at which the country ID information was recorded in to thestorage medium, and a channel setting portion that, when it isdetermined that the predetermined time period has not elapsed from thetime at which the country ID information was recorded in the storagemedium, sets a wireless channel to a frequency channel that can be usedin the country indicated by the country ID information recorded in thestorage medium.

According to the present structure, the recording portion, for example,records both the country ID information input by the user and thecurrent time as the recording-time information. The time determinationportion determines whether or not the country ID information has beenrecorded in the storage medium, and based on the recording-timeinformation, determines whether or not the predetermined time period haselapsed from the time at which the country ID information was recordedin the storage medium. If the time determination portion determines thatthe predetermined time period has not elapsed since the country IDinformation was recorded in the storage medium, the channel settingportion sets the wireless channel to a frequency channel that can beused in the country indicated by the country ID information recorded inthe storage medium. In other words, the wireless communication apparatuscan set the wireless channel to a frequency channel based on the countryID information within a predetermined time period from the time at whichthe country ID information is recorded. Here, if the predetermined timeperiod is set in accordance with the frequency at which the country inwhich the wireless communication apparatus is located changes, thecountry ID information recorded within the predetermined time periodgenerally indicates the country in which the wireless communicationapparatus is currently located. Therefore, as the wireless communicationapparatus operates based on the elapsed time period from the time atwhich the country ID information was set up, wireless communication canbe performed using an appropriate wireless channel based on highlyreliable country ID information.

Further provided are a receiving portion that receives a signaltransmitted by another wireless communication apparatus, and anextraction portion that extracts the country ID information of the otherwireless communication apparatus from the signal received by thereceiving portion. If the time determination portion determines that thecountry ID information is not recorded in the storage medium or that thepredetermined time period has elapsed from the time at which the countryID information was recorded in the storage medium, the channel settingportion may set the wireless channel based on the country ID informationof the other wireless communication apparatus extracted by theextraction portion. Here, if the predetermined time period has elapsedfrom the time at which the country ID information was recorded in thestorage portion, it is possible that the country indicated by thecountry ID information does not match the country in which the wirelesscommunication apparatus is currently located. In this type of case, thewireless communication apparatus, as described above, can automaticallyset the wireless channel based on the country ID information of theperipheral other wireless communication apparatus, and perform wirelesscommunication.

A display portion may also be provided that displays a country IDinformation input screen if the time determination portion determinesthat the country ID information is not recorded in the storage medium orthat the predetermined time period has elapsed from the time at whichthe country ID information was recorded in the storage medium. Accordingto the present structure, the wireless communication apparatus user caninput the country ID information for the country in which the user orthe wireless communication apparatus is currently located via thecountry ID information input screen displayed on the display portion. Asa result, the wireless communication apparatus can set the wirelesschannel based on extremely reliable country ID information.

A display portion may also be provided that displays a country IDinformation input screen if the other wireless communication apparatuscountry ID information extracted by the extraction portion differs fromthe country ID information recorded in the storage medium. According tothe present structure, the wireless communication apparatus user caninput the country ID information for the country in which the user orthe wireless communication apparatus is currently located via thecountry ID information input screen displayed on the display portion. Asa result, the wireless communication apparatus can set the wirelesschannel based on extremely reliable country ID information.

If the manually input country ID information of the other wirelesscommunication apparatus extracted by the extraction portion differs fromthe country ID information that is recorded in the storage medium basedon manual input, the channel setting portion may set the wirelesschannel to a frequency channel that can be used in both the countriesindicated by the country ID information of the other wirelesscommunication apparatus and the country ID information recorded in thestorage medium. For example, if the wireless communication apparatuscommunicates with the other wireless communication apparatus across anational border, the country ID information of the wirelesscommunication apparatus and the country ID information of the otherwireless communication apparatus sometimes differ. Here, if the wirelesscommunication apparatus country ID information differs from the otherwireless communication apparatus country ID information, the wirelesscommunication apparatus can set the wireless channel to a frequencychannel that can be used in both the countries indicated by both sets ofcountry ID information, and communicate with the other wirelesscommunication apparatus located in a different country.

A display portion may also be provided that displays a country IDinformation screen if the manually input country ID information of theother wireless communication apparatus extracted by the extractionportion differs from the country ID information that is recorded in thestorage medium based on manual input. According to the presentstructure, the wireless communication apparatus user can input thecountry ID information for the country in which the user or the wirelesscommunication apparatus is currently located via the country IDinformation input screen displayed on the display portion. As a result,the wireless communication apparatus can set the wireless channel basedon extremely reliable country ID information.

If the manually input country ID information of the other wirelesscommunication apparatus extracted by the extraction portion differs fromthe country ID information recorded in the storage medium, and if themanually input information chronologically precedes the recording of thecountry ID information in the storage medium, the recording portion mayupdate the country ID information recorded in the storage medium to thecountry ID information of the other wireless communication apparatus andthe channel setting portion may set the wireless channel based on thecountry ID information recorded in the storage medium. Here, thereliability of the most recently input country ID information issometimes higher. If the manual input chronologically precedes therecording of the country ID information in to the storage medium, byupdating the country ID information recorded in the storage medium tothe country ID information of the other wireless communicationapparatus, the reliability of the country ID information can beimproved.

According to another embodiment of the present invention, there is alsoprovided a wireless communication system that includes a plurality ofwireless communication apparatuses that perform wireless communicationusing a specified wireless channel and that form an ad hoc network. Eachof the wireless communication apparatuses forming part of the wirelesscommunication system includes: a recording portion that records countryID information indicating a country on the earth in to a storage medium,and that further records in to the storage medium recording-timeinformation indicating the time at which the country ID information wasrecorded in to the storage medium; a transmitting portion that transmitsa signal that includes the country ID information recorded in thestorage medium, a receiving portion that receives a signal transmittedby another wireless communication apparatus, an extraction portion thatextracts the other wireless communication apparatus country IDinformation from the signal received by the receiving portion, a timedetermination portion that, at the start-up of the wirelesscommunication apparatus, determines whether or not a predetermined timeperiod has elapsed from the time at which the country ID information wasrecorded in to the storage medium, and a channel setting portion that,when the time determination portion determines that the country IDinformation is not recorded in the storage medium, or that thepredetermined time period has elapsed from the time at which the countryID information was recorded in the storage medium, sets a wirelesschannel based on the other wireless communication apparatus country IDinformation extracted by the extraction portion.

According to another embodiment of the present invention, there isprovided a wireless communication method including the steps ofrecording country ID information that indicates a country on the earthin to a storage medium and further recording recording-time informationin to the storage medium, where the recording-time information indicatesthe time at which the country ID information was recorded in to thestorage medium. The wireless communication method further includes thestep of determining, at the start-up of the wireless communicationapparatus, whether or not a predetermined time period has elapsed fromthe time at which the country ID information was recorded, and, when itis determined that the predetermined time period has not elapsed fromthe time at which the country ID information was recorded in to thestorage medium, the step of setting the wireless communication apparatuswireless channel for wireless communication to a frequency channel thatcan be used in the country indicated by the country ID informationrecorded in the storage medium.

According to another embodiment of the present invention, there isprovided a program including instructions that command a computer tofunction as a wireless communication apparatus, the wirelesscommunication apparatus performing wireless communication using aspecified wireless channel and forming part of an ad hoc wirelessnetwork. The wireless communication apparatus includes a recordingportion that records country ID information indicating a country on theearth in to a storage medium, and that further records recording-timeinformation in to the storage medium, the recording-time informationindicating the time at which the country ID information was recorded into the storage medium. The wireless communication apparatus furtherincludes a time determination portion that, at the start-up of thewireless communication apparatus, determines whether or not apredetermined time period has elapsed from the time at which therecording-time information (indicating the time at which the country IDinformation was recorded in to the storage medium) was recorded, and achannel setting portion that, when it is determined that thepredetermined time period has not elapsed from the time at which thecountry ID information was recorded in the storage medium, sets awireless channel to a frequency channel that can be used in the countryindicated by the country ID information that is recorded in the storagemedium.

The program, for example, can cause computer hardware resourcesincluding a CPU, ROM or RAM and so on, to execute the above-describedfunctions, including the recording portion, the time determinationportion and the channel setting portion functions. In other words, theprogram can cause a computer using the program to function as theabove-described wireless communication apparatus.

According to the embodiments of the present invention described above,it is possible to set a wireless channel for an ad hoc network based onhighly reliable country ID information.

BRIEF DESCRIPTION OF THE DRAWING(S)

FIG. 1 is an explanatory diagram showing the relationship between bandgroups and sub-bands that can be used for MultiBand OFDM wirelesscommunication in the USA;

FIG. 2 is an explanatory diagram showing the relationship between bandgroups and sub-bands that can be used for MultiBand OFDM wirelesscommunication in Japan;

FIG. 3 is an explanatory diagram showing the relationship between bandgroups and sub-bands that can be used for MultiBand OFDM wirelesscommunication in Europe;

FIG. 4 is an explanatory diagram showing the relationship between bandgroups and sub-bands that can be used for MultiBand OFDM wirelesscommunication in Asian countries;

FIG. 5 is an explanatory diagram showing an example of a structure of afrequency hopping pattern for MultiBand OFDM wireless communication;

FIG. 6 is an explanatory diagram showing an example of a structure of abeacon frame for beacons transmitted and received between wirelesscommunication apparatuses in an ad hoc network;

FIG. 7 is an explanatory diagram showing an example of a structure of acountry ID code information element as an example of an informationelement;

FIG. 8 is a functional block diagram showing the structure of a wirelesscommunication apparatus according to a first embodiment of the presentinvention;

FIG. 9 is a flowchart showing the flow of a wireless communicationmethod executed at the start-up of the wireless communication apparatusaccording to the first embodiment; and

FIG. 10 is a flowchart showing the flow of a wireless communicationmethod for the operation stages after the start-up process is completedfor the wireless communication apparatus according to the firstembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the appended drawings, structural elementsthat have substantially the same function and structure are denoted withthe same reference numerals, and repeated explanation of thesestructural elements is omitted.

In the explanation of the present embodiment, after explaining thefrequency bandwidths that can be used in the USA, Japan and othercountries with reference to FIG. 1 to FIG. 4, a specific example of aMultiBand OFDM wireless communication frequency hopping pattern will beexplained with reference to FIG. 5. Next, the data structure of theinformation used in the present embodiment will be explained withreference to FIG. 6 and FIG. 7, and then the structure of the wirelesscommunication apparatus 10 according to the present embodiment will beexplained with reference to FIG. 8. Finally, an explanation will begiven of a wireless communication method that is executed using thewireless communication apparatus 10 with reference to FIG. 9 and FIG.10.

FIG. 1 is an explanatory diagram showing the relationship between bandgroups and sub-bands that can be used for MultiBand OFDM wirelesscommunication in the USA. In the USA, transmissions are allowed at acertain signal level or lower (−42 dBm) in the 3.1 GHz to 10.6 GHzbandwidth. Therefore, a first band group to a fifth band group have beendefined based on the 3.1 GHz to 10.6 GHz frequency bandwidth.

Here, as the MultiBand OFDM wireless communication method executeshopping of three sub-bands, it is necessary for the first band group,for example, to include three sub-bands. Therefore, as shown in FIG. 1,the first band group, the second band group, the third band group andthe fourth band group are defined in units of three sub-bands, in orderfrom the lowest frequency sub-band upwards.

The sub-band with the highest frequency and the sub-band with thesecond-highest frequency are defined as the fifth band group.

FIG. 2 is an explanatory diagram showing the relationship between bandgroups and sub-bands that can be used for MultiBand OFDM wirelesscommunication in Japan. In Japan, some frequency bandwidths are assignedto existing primary duties, including measurements by radio astronomicalobservatories and earth exploration satellites. In order to minimize theeffects of interference with bandwidths used for other applications, theband groups and sub-bands that can be used for MultiBand OFDM wirelesscommunication within Japan are limited in comparison to the USA.

Specifically, in Japan, as of September 2006, and as shown in FIG. 2,use of the sub-band with the lowest frequency of the sub-bands formingthe first band group, use of all the (three) sub-bands forming thesecond band group, use of the sub-band with the lowest frequency and ofthe sub-band with the second lowest frequency of the sub-bands formingthe third band group, and use of all the (two) sub-bands forming thefifth band group is restricted.

As described above, Time Frequency Interleaving (TFI) by the MultiBandOFDM wireless communication method requires 3 sub-bands, so withinJapan, MultiBand OFDM wireless communication can be performed using thefourth band group.

FIG. 3 is an explanatory diagram showing the relationship between bandgroups and sub-bands that can be used for MultiBand OFDM wirelesscommunication in Europe. In Europe, some bandwidths are assigned toexisting communication systems, including cellular telephone operatorsand broadcasters. In order to minimize the effects of interference withbandwidths used for other applications, the band groups and sub-bandsthat can be used for MultiBand OFDM wireless communication within Europeare limited in comparison to the USA.

Specifically, in Europe, as of September 2006, and as shown in FIG. 3,use of all the (three) sub-bands forming the second band group, use ofthe sub-band with the highest frequency of the sub-bands forming thefourth band group, and use of all the (two) sub-bands forming the fifthband group is restricted.

As described above, Time Frequency Interleaving (TFI) by the MultiBandOFDM wireless communication method requires 3 sub-bands, so withinEurope, MultiBand OFDM wireless communication can be performed using thefirst or the third band group.

FIG. 4 is an explanatory diagram showing the relationship between bandgroups and sub-bands that can be used for MultiBand OFDM wirelesscommunication in Asian countries. In Asian countries, frequencybandwidths are assigned to applications with reference to Japan's legalsystem, and therefore the band groups and sub-bands that can be used aresimilar to the band groups and sub-bands that can be used in Japan.

Specifically, in Asian countries, as shown in FIG. 4, use of all the(three) sub-bands forming the second band group, use of the sub-bandwith the lowest frequency and of the sub-band with the second lowestfrequency of the sub-bands forming the third band group, and use of allthe (two) sub-bands forming the fifth band group is restricted.

As described above, Time Frequency Interleaving (TFI) by the MultiBandOFDM wireless communication method requires 3 sub-bands, so in Asiancountries, MultiBand OFDM wireless communication can be performed usingthe first or the fourth band group.

As explained with reference to FIG. 1 to FIG. 4, the band groups andsub-bands that can be used for MultiBand OFDM wireless communicationdiffer from country to country. Also, a wireless communication apparatusmust perform wireless communication by adopting as a wireless channel aband group that can be used in the country in which the wirelesscommunication apparatus is located. Therefore, when a wirelesscommunication apparatus for which the wireless channel has been set upbased on the band groups that can be used in a certain country is movedto a different country, the wireless communication apparatus may nolonger be able to use the previously set wireless channel to performwireless communication in the country to which it has been moved. Forexample, if a wireless communication apparatus that has been set up touse the second band group in the USA is moved to Japan, the wirelesscommunication apparatus is no longer able to perform wirelesscommunications using the second band group.

In response to the above problem, an approach could be used in which aposition monitoring system, such as the Global Positioning System (GPS)or the like is built in to a wireless communication apparatus. The GPSsuccessively obtains the location of the country in which the wirelesscommunication apparatus is located, and the wireless channel is set inaccordance with a band group that can be used in the country for whichthe location information has been obtained. However, depending on theuser, the wireless communication apparatus may not be moved over anational border, and it is therefore not efficient to build GPS in tothe wireless communication apparatus to carry out automatic wirelesschannel setting depending on the country. The wireless communicationapparatus according to the present embodiment will be explained infurther detail later, and a particular feature of the invention is thatit allows appropriate wireless channel settings to be made without theneed for a built-in GPS or other position monitoring system.

Further, as shown in FIG. 1. to FIG. 4., of the first through fifth bandgroups, there is no band group that can be used in all countries. On theother hand, when looking at the situation in terms of sub-bands, it canbe seen that the sub-band with the highest frequency of the sub-bandsforming the third band group, the sub-band with the lowest frequency ofthe sub-bands forming the fourth band group, and the sub-band with thesecond lowest frequency of the sub-bands forming the fourth band groupcan be used in all countries. Therefore, a method is proposed where theabove-mentioned three sub-bands are used as universal sub-brands thatcan be used in all countries. In the present specification, the wirelesscommunication apparatus according to the present embodiment will beexplained on the assumption that the above sub-bands have been approvedfor common use in all countries.

The wireless communication apparatus according to the presentembodiment, as explained above, sets the wireless channel to a bandgroup that can be used in the country in which the wirelesscommunication apparatus is located. Further, the wireless communicationapparatus performs wireless communication by hopping the sub-bands thatform the wireless channel. More specifically, the wireless communicationapparatus, after performing wireless communication using one of thesub-bands that forms the wireless communication channel over a fixedperiod of time, changes the sub-band being used and performs wirelesscommunication for a fixed period of time, and repeats this operation. Byproviding diverse frequency hopping patterns to be used as sub-bandswitch patterns, it is possible to avoid interference with otherwireless communication apparatuses that are using the same band groupfor wireless communication. Below, an example of a frequency hoppingpattern will be explained with reference to FIG. 5.

FIG. 5 is an explanatory diagram showing an example of a structure of afrequency hopping pattern for MultiBand OFDM wireless communication. Inthe MultiBand OFDM wireless communication method, a total of 7 physicalchannels are available as frequency hopping patterns for 3 sub-bands.Each of the sub-bands used in the explanation below, namely the firstsub-band, the second sub-band and the third sub-band, form a same bandgroup and each sub-band differs from the others.

For example, the physical channel defined by Code 1 (the frequencyhopping pattern) is a pattern in which the first sub-band, the secondsub-band and the third sub-band that form a certain band group areswitched in a repeating pattern, as follows: first sub-band, secondsub-band, third sub-band, first sub-band, second sub-band, thirdsub-band and so on.

The physical channel defined by Code 2 is a pattern in which the firstsub-band, the second sub-band and the third sub-band that form a certainband group are switched in a repeating pattern as follows: firstsub-band, third sub-band, second sub-band, first sub-band, thirdsub-band, second sub-band and so on.

The physical channel defined by Code 3 is a pattern in which the firstsub-band, the second sub-band and the third sub-band that form a certainband group are switched in a repeating pattern as follows: firstsub-band, first sub-band, second sub-band, second sub-band, thirdsub-band, third sub-band and so on.

The physical channel defined by Code 4 is a pattern in which the firstsub-band, the second sub-band and the third sub-band that form a certainband group are switched in a repeating pattern as follows: firstsub-band, first sub-band, third sub-band, third sub-band, secondsub-band, second sub-band and so on.

The physical channel defined by Code 5 is a pattern in which frequencyhopping of the first sub-band, the second sub-band and the thirdsub-band that form a certain band group is not performed, and the firstsub-band is used continuously.

The physical channel defined by Code 6 is a pattern in which frequencyhopping of the first sub-band, the second sub-band and the thirdsub-band that form a certain band group is not performed, and the secondsub-band is used continuously. In the same way, the physical channeldefined by Code 7 is a pattern in which frequency hopping of the firstsub-band, the second sub-band and the third sub-band that form a certainband group is not performed, and the third sub-band is usedcontinuously.

In this way, a diverse number of MultiBand OFDM wireless communicationfrequency hopping patterns are available. By using the frequency hoppingpatterns defined by codes differing for each wireless network,interference is minimized, and a limited frequency bandwidth can beefficiently used. Next, an explanation will be given of the informationthat is transmitted and received using the wireless communicationapparatus with MultiBand OFDM wireless communication.

In an ad hoc network, there is no base station for unified control ofcommunications. Therefore, methods have been proposed in which wirelesscommunication apparatuses that form part of an ad hoc network transmitand receive beacons used as mutual communication control information, inorder to realize ad hoc wireless communication. FIG. 6 shows an exampleof the structure of a beacon frame that contributes to the establishmentof ad hoc wireless communication in the above way.

FIG. 6 is an explanatory diagram showing an example of a structure of abeacon frame for beacons transmitted and received between wirelesscommunication apparatuses in an ad hoc network. The beacon frameincludes established control information, including a MAC headerinformation 60, a header check sequence (HCS) 61, beacon parameters 62,an information element (1) 63, an information element (2) 64, aninformation element (N) 65 and a frame check sequence (FCS) 66.

The MAC header information 60 further includes frame control information601, a destination address 602 that identifies the receiving wirelesscommunication apparatus, a source address 603 that identifies thetransmitting wireless communication apparatus, sequence controlinformation 604 including a sequence number and the like, and accesscontrol information 605 that holds the parameters necessary for accesscontrol and the like.

The beacon parameters 62 further include a device identifier 621 thatholds the wireless communication apparatus MAC address information andthe like, a beacon slot number 622 that indicates the beacon slot beingused by the wireless communication apparatus to transmit the beacon, anddevice control information 623 that includes information unique to thewireless communication apparatus.

In addition, information elements can be added freely to the beaconframe as payload information, and, as an example of informationelements, FIG. 6 shows the information element (1) 63, the informationelement (2) 64, and the information element (N) 65. The N referred tohere indicates the number of information elements added to the beaconand transmitted, and the number of information elements N may differwith each beacon that is transmitted.

The frame check sequence (FCS) 66 is information used to detect errorsin the beacon frame. The beacon frame 20 may be structured such thateach of the above parameters can be added or deleted as necessary. Anexample of a specific information element structure will next beexplained with reference to FIG. 7.

FIG. 7 is an explanatory diagram showing an example of a structure of acountry ID code information element as an example of an informationelement. The country ID information element includes an element ID 701,an information length 702, an international region code 703, a countryID code 704, an in-country region ID code 705, user settings information706, input date/time information 707, received date/time information708, power supply information 709, and temporary restriction on useinformation 710.

The element ID 701 is ID information attached to each of the informationelements and that indicates what each information element is related to.Therefore, the element ID 701 shown in FIG. 7 indicates a country IDcode information element. The information length 702 indicates the datasize of the country ID code information element.

The international region code 703 is information that indicates majorregions on the earth (North America, South America, Northern Europe,Europe, Asia, Africa, Australia and so on), and can be obtained, forexample, from manual input by a user or from peripheral wirelesscommunication apparatuses. The major region of the world indicated bythe international region code 703 is handled, for example, as the regionin which the wireless communication apparatus is currently located.

The country ID code 704 is country ID information that indicates anindividual country (Japan, the USA, Great Britain, Germany, China and soon), and can be obtained, for example, from manual input by a user orfrom peripheral wireless communication apparatuses. The countryindicated by the country ID code 704, is handled, for example, as thecountry in which the wireless communication apparatus is currentlylocated.

The in-country region ID code 705 indicates a more detailed regionrelating to the country indicated by the country ID code 704 (the Kantoregion, the Chubu region, the Kinki region, Kyushu, Shikoku, Hokkaido,New York State, Washington State and so on), and can be obtained, forexample, from manual input by a user or from peripheral wirelesscommunication apparatuses. The more detailed region in the countryindicated by the in-country region ID code 705 is handled, for example,as the region in which the wireless communication apparatus is currentlylocated.

The user settings information 706 is information that indicates whetherthe above-described international region code 703, the country ID code704, and the in-country region ID code 705 and so on have been directlyset up through manual input by a user, or have been set up based oninformation obtained from a peripheral wireless communication apparatus.

When the above-described international region code 703, the country IDcode 704 and the in-country region ID code 705 and so on have been setupbased on manual input by the user, the input date/time information 707is recording-time information that indicates the time at which manualinput by the user was performed, where the recording-time informationincludes the month, date and time.

For example, the input date/time information 707 may indicate the timeas it is at the time of manual input by the user, may indicate the timeperiod that has elapsed from the time at which the time was manuallyinput by the user, may be a timer value where the countdown started atthe time at which the time was manually input by the user, or may beinformation that indicates whether a predetermined amount of time haselapsed or not from the time at which the time was manually input by theuser. The input date/time information 707 may also be information thatindicates the time at which the international region code 703, thecountry ID code 704 and the in-country region ID code 705 and so on weresetup by manual input by the user.

When the above-described international region code 703, the country IDcode 704 and the in-country region ID code 705 and so on have been setup based on information received from a peripheral wirelesscommunication apparatus, the received date/time information 708 isrecording-time information that indicates the time at which theinformation was received, the recording-time information including themonth, date and time.

For example, the received input date/time information 708, in the sameway as the input date/time information 707, may indicate the time atwhich the information was received, may indicate the time period thathas elapsed from the time at which the information was received, may bea timer value where the countdown started at the time at which theinformation was received, or may be information that indicates whether apredetermined amount of time has elapsed or not from the time at whichthe information was received. The received date/time information 708 mayalso be information that indicates the time at which the internationalregion code 703, the country ID code 704 and the in-country region IDcode 705 and so on were set up based on information received from aperipheral wireless communication apparatus.

The power supply information 709 indicates the status of the powersupply for the wireless communication apparatus, while the temporaryrestriction on use information 710 is information that shows that theuse of the wireless communication or the band group is temporarilyrestricted. Each of the above-described data that form the country IDcode information element may be added or deleted as necessary. Also, thewireless communication apparatus may be set up to transmit a beacon thatdoes not include a country ID code information element, and to includethe country ID code information element in the beacon and transmit it ifthere is a request from another wireless communication apparatus toinclude the country ID code information element.

An explanation has been given above of the frequency bandwidths andinformation used in an ad hoc network. Next, the functions andoperations of the wireless communication apparatuses that form the adhoc network will be explained with reference to FIG. 8 to FIG. 11.

FIG. 8 is a functional block diagram showing the structure of a wirelesscommunication apparatus 10 according to the present embodiment. Thewireless communication apparatus 10 according to the present embodiment,together with at least one other peripheral wireless communicationapparatus 11, forms an ad hoc network (a wireless communication system8) and can perform wireless communication using an appropriate bandgroup.

This type of wireless communication apparatus 10 includes a firstantenna 101A, a second antenna 101B, a high frequency processing portion102, a receiving PHY base band processing portion 103, a transmittingPHY base band processing portion 104, a beacon information analysisportion 105, a country ID code extraction portion 106, a country ID codeconformity determination portion 107, a set-up date/time informationdetermination portion 108, a display interface 109, an input interface110, a date/time information storage portion 111, a country ID codestorage portion 112 to store the country ID code for the wirelesscommunication apparatus 10, a country-based usable band storage portion113, a band group setting portion 115, and a beacon information settingportion 116.

The first antenna 101A and the second antenna 101B possess functions toact as the transmitting portion and the receiving portion for thewireless transmission and reception of signals. Also, a structure may beadopted in which the first antenna 101A or the second antenna 101B isused, depending on the frequency bandwidth, the signal characteristics,or the directivity and so on of the transmitted and received wirelesssignals. In the example shown in FIG. 8, the wireless communicationapparatus 10 includes more than one antenna, but the wirelesscommunication apparatus 10 may include one antenna only.

The high frequency processing portion 102 converts a signal receivedfrom the first antenna 101A or the second antenna 101B in to a basebandsignal, and converts a baseband signal for transmission in to a highfrequency signal. The high frequency processing portion 102 can converta baseband signal in to a high frequency signal in the band group(wireless channel) set up by the band group setting portion 115.

The receiving PHY baseband processing portion 103 extracts theinformation in the beacon frame from the signal converted by thehigh-frequency processing portion 102, and outputs the extractedinformation to the beacon information analysis portion 105. Thetransmitting PHY baseband processing portion 104 converts theinformation to be included in the beacon frame in to a baseband signalthrough processing of a predetermined physical layer, and outputs thebaseband signal to the high-frequency processing portion 102.

The information stored in the beacon frame transmitted by the otherwireless communication apparatus 11 is input from the receiving PHYbaseband processing portion 103 to the beacon information analysisportion, and, based on the information included in the beacon frame, thebeacon information analysis portion 105 performs processing, includingsynchronization with the other wireless communication apparatus 11 (forexample, superframe synchronization), parameter conversion and the like.

The country ID code extraction portion 106 acts as an extraction portionthat extracts the country ID code included in the beacon frame andoutputs the extracted code to the country ID code conformitydetermination portion 107. For example, the country ID code extractionportion 106 refers to the beacon frame, and outputs the country ID codeset up by the other wireless communication apparatus 11 to the countryID code conformity determination portion 107, along with the usersettings information 706, the input date/time information 707 and thereceived date/time information 708 (see FIG. 7 for details).

The country ID code conformity determination portion 107 determineswhether or not the country ID code set up by the other wirelesscommunication apparatus 11 conforms with the country ID code set up inthe wireless communication apparatus 10 (the country ID code beingstored in the country ID code storage portion 112). Also, the country IDcode conformity determination portion 107, based on the user settingsinformation 706 included in the beacon frame transmitted by the otherwireless communication apparatus 11, determines whether the country IDcode set up in the other wireless communication apparatus 11 wasmanually input by the user or not.

If the country ID code conformity determination portion 107 determinesthat the country ID code set up in the other wireless communicationapparatus 11 differs from the country ID code set in the wirelesscommunication apparatus 10, the set-up date/time informationdetermination portion 108 compares the date and time information.Specifically, the set-up date/time information determination portion 108ascertains the time at which the country ID code was set up in the otherwireless communication apparatus 11, based on the input date/timeinformation or the received date/time information, and determines thechronological relationship between the ascertained time and the set-uptime for the country ID code in the wireless communication apparatus 10(the time at which the country ID code was recorded in the country IDcode storage portion 112).

In addition, the set-up date/time information determination portion 108possesses functions to act as a time determination portion thatdetermines whether or not a predetermined time period has elapsed fromthe time at which the wireless communication apparatus 10 country IDcode was set up. In the same way, the set-up date/time informationdetermination portion 108 determines whether or not a predetermined timeperiod has elapsed from the time at which the other wirelesscommunication apparatus 11 country ID code was set up. Theabove-mentioned predetermined time period may be a time periodestablished in advance, for example, 8 hours, 1 day, 1 month or 1 year,or may be a dynamic value calculated from country ID code changes or thelike logged on the wireless communication apparatus 10 in the past. Forexample, the predetermined time period may be set up such that thehigher the frequency of changes to the country ID code in the wirelesscommunication apparatus 10, the lower is the value of the predeterminedtime period.

The display interface 109 includes a screen generating portion (notshown in the figures) that generates a country ID code input screen asneeded, and a display portion (not shown in the figures) that displaysthe country ID code input screen generated by the screen generationportion. If, for example, a country ID code is not set in the wirelesscommunication apparatus 10 at the start-up of the wireless communicationapparatus 10, or if, at the start-up of the wireless communicationapparatus 10, a predetermined period of time has elapsed from the timeat which the wireless communication apparatus 10 country ID code was setup, the display interface 109 may display the country ID code inputscreen.

Here, if the predetermined time period is set in accordance with thefrequency at which the country in which the wireless communicationapparatus 10 is located changes, the country ID code generally indicatesthe country in which the wireless communication apparatus 10 is locatedwhile within the predetermined time period from the time at which thesetting was made. On the other hand, if the predetermined time periodhas elapsed from when the setting was made, the country ID codesometimes indicates a country that differs from the country in which thewireless communication apparatus 10 is located. If, at the start-up ofthe wireless communication apparatus 10, the predetermined time periodhas elapsed since the time at which the wireless communication apparatus10 country ID code was set up, the display interface 109 displays thecountry ID code input screen and prompts the user to input the countryID code, thus realizing input of a highly reliable country ID code.

The display interface 109 may also display the country ID code inputscreen if the country ID code conformity determination portion 107determines that the country ID code set up in the other wirelesscommunication apparatus 11 differs from the wireless communicationapparatus 10 country ID code. The display interface 109 may also displaythe country ID code input screen if the country ID code conformitydetermination portion 107 determines that the country ID code set up inthe other wireless communication apparatus 11 differs from the wirelesscommunication apparatus 10 country ID code and the country ID codes forboth the wireless communication apparatus 10 and the other wirelesscommunication apparatus 11 were set up based on manual input by theuser.

When the country ID code conformity determination portion 107 determinesthat the country ID code set up in the other wireless communicationapparatus 11 differs from the wireless communication apparatus 10country ID code, it is often difficult to determine which of the countryID codes is correct. Here, when the country ID code conformitydetermination portion 107 determines that the country ID code set up inthe other wireless communication apparatus 11 differs from the wirelesscommunication apparatus 10 country ID code, the display interface 109displays the country ID code input screen and prompts the user to inputthe country ID code. It can therefore be expected that the user willinput the country ID code indicating the country in which the wirelesscommunication apparatus 10 is currently located.

The input interface 110 possesses functions to act as an operatingportion, for the user to perform information input operations inrelation to the wireless communication apparatus 10 or to detectdesignated operations. The input interface 110 detects, for example, theinput operation when the user inputs the country ID code. This type ofinput interface 110 may be a device for the user to input information,such as a mouse, a keyboard, a touch panel, a button or buttons, amicrophone, a switch or switches, or a lever or the like.

The date/time information storage portion 111 includes a date/timeinformation memory portion (not shown in the figures) that stores set-update/time information, including the input date/time information 707 andthe received date/time information 708 relating to the wirelesscommunication apparatus 10 explained above with reference to FIG. 7, anda date/time information recording portion (recording portion) (not shownin the figures) that records the set-up date/time information in to thedate/time information memory portion. For example, the date/timeinformation recording portion may record the time that the country IDcode was input by the user via the input interface 110 in to to thedate/time information memory portion, or may record the time at whichthe country ID code was recorded in to the country ID code storageportion 112 in to the date/time information memory portion.

The date/time information memory portion may be, for example, anon-volatile memory such as an electronically erasable programmableread-only memory (EEPROM), an erasable programmable read-only memory(EPROM), or the like, a magnetic disk such as a hard disk, a flexibledisk, or the like, an optical disk such as a compact disc recordable(CD-R), a compact disc rewritable (CD-RW), a digital versatile discrecordable (DVD-R), a digital versatile disc rewritable (DVD-RW), adual-layer digital versatile disc recordable (DVD+R), a dual-layerdigital versatile disc rewritable (DVD+RW), a digital versatile discrandom access memory (DVD-RAM), a Blu-ray™ disc recordable (BD-R), adual-layer Blu-ray™ disc recordable (BD-RE), or the like, or amagneto-optical (MO) disk.

The country ID code storage portion 112 includes a country ID codememory portion that stores the country ID code 704 relating to thewireless communication apparatus 10 explained above with reference toFIG. 7, and a country ID code recording portion (recording portion) thatrecords the country ID code 704 relating to the wireless communicationapparatus 10 explained above with reference to FIG. 7 in to the countryID code memory portion. For example, the country ID code recordingportion may record the country ID code input by the user via the inputinterface 110 in to the country ID code memory portion.

The country ID code recorded in the country ID code memory portion ishandled as the country ID code set up in the wireless communicationapparatus 10, and the recording of the country ID code in to the countryID code memory portion is handled as the setting up of the wirelesscommunication apparatus 10 country ID code. The country ID code memoryportion may be a memory medium in the same way as the above-describeddate/time information memory portion and may be integrated with thedate/time information memory portion.

In addition, if a country ID code is not recorded in the country ID codememory portion, or if the predetermined time period has elapsed from thetime at which the country ID code was recorded in the country ID codememory portion, the country ID code recording portion may record thecountry ID code set up in the other wireless communication apparatus 11in to the country ID code memory portion. Alternatively, if the wirelesscommunication apparatus 10 is operating dependent on the country ID codereceived from the other wireless communication apparatus 11, the countryID code recording portion may record the country ID code received fromthe other wireless communication apparatus 11 in to the country ID codememory portion.

If the country ID code recording portion records the country ID code into the country ID code memory portion based on input by the user via theinput interface 110, the fact that the country ID code has been recordedvia manual input by the user may also be recorded.

The country-based usable band storage portion 113 stores the band groupsthat can be used in each country, extracts the band group or band groupsthat can used in the country indicated by the country ID code recordedin the country ID code storage portion 112, and outputs to the bandgroup setting portion 115.

The band group setting portion 115 functions as a channel settingportion that sets the wireless channel to be used for wirelesscommunication from one of the usable band groups that have been inputfrom the country-based usable band storage portion 113, sets thewireless channel frequency hopping pattern, and outputs the set bandgroup and frequency hopping pattern to the high frequency processingportion 102.

If the country ID code conformity determination portion 107 determinesthat the country ID code set up in the other wireless communicationapparatus 11 differs from the wireless communication apparatus 10country ID code, the band group setting portion 115 may set the wirelesschannel to sub-bands that can be universally used in all countries.According to the present structure, it is possible to perform normalwireless communication even when it is difficult to determine which iscorrect of the country ID code set up in the other wirelesscommunication apparatus 11 or the wireless communication apparatus 10country ID code.

Also, at the start-up of the wireless communication apparatus 10, if theset-up date/time information determination portion 108 determines thatthe predetermined time period has not elapsed since the time at whichthe country ID code was set in the wireless communication apparatus 10,the band group setting portion 115 may set the wireless channel to beused for the wireless communication based on the band group output bythe country-based usable band storage portion 113, that output beingbased on the country ID code recorded in the country ID code storageportion 112.

Here, if the predetermined time period is set in accordance with thefrequency at which the country where the wireless communicationapparatus 10 is located changes, within the predetermined time periodfrom when the set-up was made, the country ID code generally indicatesthe country in which the wireless communication apparatus 10 is located.On the other hand, if the predetermined time period has elapsed fromwhen the set-up was made, the country ID code sometimes indicates acountry that differs from the country in which the wirelesscommunication apparatus 10 is located. Therefore, according to thewireless communication apparatus 10 that operates based on whether thepredetermined period of time has elapsed or not from the time at whichthe country ID code was set, wireless communication can be performedusing an appropriate band group based on a highly reliable country IDcode.

The beacon information setting portion 116 can generate an informationelement based on the information stored in the date/time informationstorage portion 111 and the country ID code storage portion 112, and canadd the information element to the beacon when necessary. Any of theblocks shown in FIG. 8 may be integrated or deleted as necessary, or maybe further segmentalized. New blocks may also be added. The wirelesscommunication apparatus 11 is at least one wireless communicationapparatus that exists peripherally to the wireless communicationapparatus 10. As the structure of the wireless communication apparatus11 can be essentially identical to that of the wireless communicationapparatus 10, an explanation of the wireless communication apparatus 11is omitted here.

The structure of the wireless communication apparatus 10 according tothe present embodiment has been explained with reference to FIG. 8.Next, the wireless communication method using the wireless communicationapparatus 10 will be explained with reference to FIG. 9 and FIG. 10.

FIG. 9 is a flowchart showing the flow of a wireless communicationmethod executed at the start-up of the wireless communication apparatus10. When the power is switched on, the wireless communication apparatus10 first performs an initialization process (step S201). Next, thewireless communication apparatus 10 set-up date/time informationdetermination portion 108 determines whether or not a country ID codehas previously been recorded in the country ID code storage portion 112(step S202). If it determines that a country ID code has been recorded,the set-up date/time information determination portion 108 acquiresset-up date/time information from the date/time information storageportion 111 (step S203), and determines whether the predetermined timeperiod has elapsed or not since the time at which the country ID codewas set. In other words, it determines whether or not the country IDcode is within a valid time period or not (step S204).

If it is determined in step S204 that the country ID code is within thevalid time period, the band group setting portion 115 sets the wirelesschannel to a band group that can be used in the country indicated by thecountry ID code recorded in the country ID code storage portion 112(step S205).

If it is determined in step S202 that a country ID code has notpreviously been recorded in the country ID code storage portion 112, thefirst antenna 101A or the second antenna 101B receive a beacon from theother wireless communication apparatus 11 (step S206). Next, if a beaconhas been received in step S206, the beacon information analysis portion105 and the country ID code extraction portion 106 acquire the set-update/time information included in the beacon, such as the inputdate/time information or the received date/time information etc. (stepS207 and step S208).

Then, the set-up date/time information determination portion 108, basedon the set-up date/time information acquired in step S208, determineswhether the country ID code set in the other wireless communicationapparatus 11 is within the valid time period or not (step S209). If itis determined that the country IL) code set in the other wirelesscommunication apparatus 11 is within the valid time period, the beaconinformation analysis portion 105 and the country ID code extractionportion 106 acquire the country ID code set in the other wirelesscommunication apparatus 11 (step S210).

After that, if there is only one country ID code set in the otherwireless communication apparatus 11 (step S211), the country ID codestorage portion 112 records the country ID code set in the otherwireless communication apparatus 11 (step S212). Next, the date/timeinformation storage portion 111 records the received set-up date/timeinformation (step S213).

If a beacon was not received in step S206, the display interface 109displays a country ID code input screen (step S207 and step S214). Then,if the country ID code was manually input by the user via the inputinterface 110, the country ID code storage portion 112 records themanually input country ID code (step S215 and step S216). Further, thedate/time information storage portion 111 records the country ID codeset-up date/time information (step S217).

If no country ID code was input using the country ID code input screendisplayed by the display interface 109 in step S214, the band groupsetting portion 115 sets the wireless channel to sub-bands that can beuniversally used in all countries (step S218). Then the displayinterface 109, as necessary, generates a display indicating that nocountry ID code has been set (step S219), and the country ID codestorage portion 112 records “no country ID code” as the country ID code(step S220).

After step S205, after step S213, or after step S220, the wirelesscommunication apparatus 10 sets up a super frame (step S221), sets upthe beacon slot for the wireless communication apparatus 10 to receive abeacon (step S222), and sets up beacon transmission (step S223).

FIG. 10 is a flowchart showing the flow of a wireless communicationmethod relating to the operation stages after the start-up process iscompleted for the wireless communication apparatus 10. Specifically,FIG. 10 shows the flow of the wireless communication method in relationto the stages of an ad hoc network that operates by the periodicexchange of beacons.

First, if the wireless communication apparatus 10 is currently in abeacon period, when the beacon slot set as the time slot to transmit thebeacon by the wireless communication apparatus 10 arrives, the wirelesscommunication apparatus 10 transmits a beacon including informationelements that include the country ID code stored in the country ID codestorage portion 112 and the set-up date/time information stored in thedate/time information storage portion 111 (step S231, step S232 and stepS233). If the wireless communication apparatus 10 is not currently in abeacon period, and after the beacon has been transmitted in step S233,the wireless communication apparatus 10 returns to the step S231process.

During a beacon period, if there is no beacon slot from the wirelesscommunication apparatus 10, the first antenna 101A or the second antenna101B receives a beacon from the other wireless communication apparatus11 (step S234). When the beacon is received in step S234, if country IDcode information element is included in the received beacon, the countryID code extraction portion 106 extracts the country ID code from thebeacon (step S235 to step S237).

Next, the country ID code conformity determination portion 107determines whether or not the country ID code extracted by the countryID code extraction portion 106 differs from the country ID code set upin the wireless communication apparatus 10 (step S238). If the countryID code conformity determination portion 107 determines that the countryID code extracted by the country ID code extraction portion 106 differsfrom the country ID code set up in the wireless communication apparatus10, it then determines whether or not the country ID code set up in thewireless communication apparatus 10 was manually input by the user (stepS239).

If the country ID code set up in the wireless communication apparatus 10is determined not to have been manually input by the user, it is nextdetermined whether or not the country ID code set in the correspondingwireless communication apparatus 11 has been manually input by the user(step S240). If it is determined that the country ID code set in thecorresponding wireless communication apparatus 11 has been manuallyinput by the user, the country ID code extraction portion 106 extractsthe country ID code set-up date/time information from the beacontransmitted by the wireless communication apparatus 11 (step S241).

Then, based on the wireless communication apparatus 11 country ID codeset-up date/time information extracted by the country ID code extractionportion 106, the set-up date/time information determination portion 108determines whether or not the wireless communication apparatus 11country ID code is within the valid time period (step S242). The set-update/time information determination portion 108 may also determine thechronological relationship between the time at which the wirelesscommunication apparatus 11 country ID code was set up and the time atwhich the wireless communication apparatus 10 country ID code was setup.

If the set-up date/time information determination portion 108 determinesthat the wireless communication apparatus 11 country ID code is withinthe valid time period, the country ID code storage portion 112 recordsand sets up the wireless communication apparatus 11 country ID code asthe wireless communication apparatus 10 country ID code (step S243). Asa result, the band group setting portion 115 can set the wirelesschannel to a band group that can be used in the country indicated by thewireless communication apparatus 11 country ID code. If the set-update/time information determination portion 108 determines that thewireless communication apparatus 11 country ID code is not within thevalid time period, operations continue based on the country ID code setup in the wireless communication apparatus 10. Alternatively, in stepS243, the country ID code storage portion 112 may record and set as thewireless communication apparatus 10 country ID code whichever country IDcode was more recently set up of the wireless communication apparatus 11country ID code and the wireless communication apparatus 10 country IDcode.

In step S240, if the country ID code set up in the correspondingwireless communication apparatus 11 is determined not to be based onmanual input by the user, the band group setting portion 115 sets thewireless channel to sub-bands that can be universally used in allcountries (step S244). Then, as necessary, the display interface 109indicates that the country ID code information has not yet been set up(step S245) and the country ID code storage portion 112 records “nocountry ID code” as the country ID code (step S246). Alternatively, thesystem may be set up so that the same processing as the branch describedbelow can be performed, as shown by the dashed line in FIG. 10.

Also, in step S239, if the country ID code set up in the wirelesscommunication apparatus 10 is determined to be based on manual input bythe user, the country ID code extraction portion 106 extracts thecountry ID code set-up date/time information from the beacon transmittedby the wireless communication apparatus 11 (step S247). Then, thedate/time information determination portion 108 determines which of theset-up date/time information is more recent, that of the correspondingwireless communication apparatus 11 or that of the wirelesscommunication apparatus 10 (step S248). If the set-up date/timeinformation of the corresponding wireless communication apparatus 11 isdetermined to be more recent, and if there are fewer restrictionsrelating to the band group that can be used with the wirelesscommunication apparatus 11 country ID code than with the country ID codecurrently set up in the wireless communication apparatus 10 (step S249),the display interface 109 indicates that there is no conformity betweenthe country ID codes (step S250). Then, the wireless communicationapparatus 10 continues operations based on the country ID code currentlyset in the wireless communication apparatus 10.

If the set-up date/time information of the corresponding wirelesscommunication apparatus 11 is determined to be more recent, and if thereare greater restrictions relating to the band group that can be usedwith the wireless communication apparatus 11 country ID code than withthe country ID code currently set up in the wireless communicationapparatus 10, the display interface 109 displays the country ID codeinput screen (step S251). Then, if the country ID code is manually inputby the user via the input interface 110, the country ID code storageportion 112 records the manually input country ID code (step S252 andstep S253).

Further, the date/time information storage portion 111 records thecountry ID code set-up date/time information (step S254). If the countryID code is not manually input by the user via the input interface 110,the band group setting portion 115 sets the wireless channel tosub-bands that are common to both the band group or band groups that canbe used in the country indicated by the wireless communication apparatus11 country ID code and to the band group or band groups that can be usedin the country indicated by the wireless communication apparatus 10country ID code (step S244).

If the beacon received by the wireless communication apparatus 10 doesnot include a country ID code for a country that is not the same as thewireless communication apparatus 10 country ID code, or if the identicalcountry ID code in the wireless communication apparatus 10 is set in thewireless communication apparatus 11 and the set-up date/time informationfor the wireless communication apparatus 10 is more recent, the wirelesscommunication apparatus 10 continues operations based on the country IDcode set up in the wireless communication apparatus 10. Also, after theseries of processes shown in FIG. 10 to once more set up the country IDcode is complete, or if not within the beacon period, the series ofprocesses are exited, and processes are not executed until the countryID code determination process is performed by once more receiving abeacon.

As explained above, the wireless communication apparatus 10 according tothe present embodiment can perform wireless communication using a bandgroup based on the legal prescriptions of the country in which thewireless communication apparatus 10 is located and can form part of anad hoc network. Also, the wireless communication apparatus 10, byoperating based on a time period elapsed from the time at which thecountry ID code is set up, can perform wireless communication using anappropriate wireless channel based on a highly reliable country ID code.Also, as the wireless communication apparatus 10 can operate accordingto the country ID code of the peripheral wireless communicationapparatus 11, it can perform operations in the country in which it islocated without a device for inputting the country ID code in to thewireless communication apparatus 10.

In addition, if the country ID code set up in the wireless communicationapparatus 10 differs from the country ID code set up in the wirelesscommunication apparatus 11, the band groups set up are the band groupsthat can be used in both the countries indicated by each of the countryID codes, thus preventing illegitimate radio waves from crossingnational borders. Further, if the country ID code set up in the wirelesscommunication apparatus 10 and the country ID code set up in theperipheral wireless communication apparatus 11 are not geographicallycontinuous, the wireless communication apparatus 10 displays the countryID code input screen and prompts manual input by the user, thusminimizing intentional transmission of signals using a band group thatshould not be used.

Also, as the wireless communication apparatus 10 transmits beacons thatinclude set-up date/time information, it is possible to determine whichcountry ID code has most recently been set up, that of the wirelesscommunication apparatus 10 or that of other wireless communicationapparatuses, including the peripheral wireless communication apparatus11. Additionally, based on the set-up date/time information in thewireless communication apparatus 10, it is possible to determine whetheror not it is possible to use band groups (frequency bandwidths) forwhich use is approved based on time restrictions.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

For example, if the wireless communication apparatus 10 country ID codeand the peripheral wireless communication apparatus 11 country ID codeare not geographically continuous, the wireless communication apparatus10 may be structured to stop operations if the country ID code is notmanually input by the user within a specific time period. The presentstructure offers the benefit of preventing or stopping wirelesscommunication using an illegitimate band group.

Each of the steps performed by the wireless communication apparatus 10of the present specification do not necessary need to be performedchronologically and in the order noted on the flow charts, but mayinclude processing performed in parallel or individually (for example,parallel processing or object processing).

Also, a computer program may be provided that causes the hardware builtin to the wireless communication apparatus 10, including the CPU, ROMand RAM and the like, to perform the same functions as each member ofthe wireless communication apparatus 10 structure described above. Arecording medium is also provided that stores the computer program. Eachof the functional blocks shown in the functional block diagram in FIG. 8can be formed by hardware, and the series of processes can also berealized by hardware.

1. A wireless communication apparatus that performs wirelesscommunication using a specified wireless channel and that forms part ofan ad hoc wireless network, comprising: a recording portion that recordscountry ID information indicating a country on the earth in to a storagemedium, and that further records in to the storage medium recording-timeinformation indicating the time at which the country ID information wasrecorded in to the storage medium; a time determination portion that, atstart-up of the wireless communication apparatus, determines whether apredetermined time period has elapsed from the time at which the countryID information was recorded in to the storage medium, based on therecording-time information; and a channel setting portion that, when itis determined that the predetermined time period has not elapsed sincethe time at which the country ID information was recorded in the storagemedium, sets a wireless channel to a frequency channel that can be usedin the country indicated by the country ID information recorded in thestorage medium.
 2. The wireless communication apparatus according toclaim 1, further comprising: a receiving portion that receives a signaltransmitted by another wireless communication apparatus; and anextraction portion that extracts the country ID information of the otherwireless communication apparatus from the signal received by thereceiving portion, wherein if the time determination portion determinesthat the country ID information is not recorded in the storage medium orthat the predetermined time period has elapsed since the country IDinformation was recorded in the storage medium, the channel settingportion sets the wireless channel based on the country ID information ofthe other wireless communication apparatus extracted by the extractionportion.
 3. The wireless communication apparatus according to claim 1,further comprising: a display portion that displays an input screen ifthe time determination portion determines that the country IDinformation is not recorded in the storage medium or that thepredetermined time period has elapsed since the country ID informationwas recorded in the storage medium.
 4. The wireless communicationapparatus according to claim 2, further comprising: a display portionthat displays a country ID information input screen if the country IDinformation of the other wireless communication apparatus extracted bythe extraction portion differs from the country ID information recordedin the storage medium.
 5. The wireless communication apparatus accordingto claim 2, wherein if the manually input country ID information of theother wireless communication apparatus extracted by the extractionportion differs from the country ID information that is recorded in thestorage medium based on manual input, the channel setting portion setsthe wireless channel to a frequency channel that can be used in both thecountries indicated by the country ID information of the other wirelesscommunication apparatus and the country ID information recorded in thestorage medium.
 6. The wireless communication apparatus according toclaim 2, further comprising: a display portion that displays the countryID information screen if the manually input country ID information ofthe other wireless communication apparatus extracted by the extractionportion differs from the country ID information that is recorded in thestorage medium based on manual input.
 7. The wireless communicationapparatus according to claim 2, wherein if the manually input country IDinformation of the other wireless communication apparatus extracted bythe extraction portion differs from the country ID information recordedin the storage medium, and if the manually input informationchronologically precedes the recording of the country ID information inthe storage medium, the recording portion updates the country IDinformation recorded in the storage medium to the country ID informationin the other wireless communication apparatus, and the channel settingportion sets the wireless channel based on the country ID informationrecorded in the storage medium.
 8. A wireless communication system thatincludes a plurality of wireless communication apparatuses that performwireless communication using a specified wireless channel and that forman ad hoc wireless network, each of the wireless communicationapparatuses comprising: a recording portion that records country IDinformation indicating a country on the earth in to a storage medium,and that further records in to the storage medium recording-timeinformation indicating the time at which the country ID information wasrecorded in to the storage medium; a transmission portion that transmitsa signal that includes the country ID information recorded in thestorage medium; a receiving portion that receives the signal transmittedby another wireless communication apparatus; an extraction portion thatextracts the country ID information of the other wireless communicationapparatus from the signal received by the receiving portion; a timedetermination portion that, at start-up of the wireless communicationapparatus, determines whether a predetermined time period has elapsedfrom the time at which the country ID information was recorded in to thestorage medium; and a channel setting portion that, when the timedetermination portion determines that the country ID information is notrecorded in the storage medium or that the predetermined time period haselapsed since the time at which the country ID information was recordedin the storage medium, sets a wireless channel based on the country IDinformation of the other wireless communication apparatus extracted bythe extraction portion.
 9. A wireless communication method, comprisingthe steps of: recording country ID information that indicates a countryon the earth in to a storage medium; recording recording-timeinformation in to the storage medium that indicates the time at whichthe country ID information was recorded in to the storage medium; anddetermining, at the start-up of the wireless communication apparatus,whether a predetermined time period has elapsed from the time at whichthe country ID information was recorded, wherein when it is determinedthat the predetermined time period has not elapsed since the country IDinformation was recorded in the storage medium, setting the wirelesscommunication apparatus wireless channel for wireless communication to afrequency channel that can be used in the country indicated by thecountry ID information recorded in the storage medium.
 10. A programcomprising instructions that command a computer to function as awireless communication apparatus that performs wireless communicationusing a specified wireless channel and forms part of an ad hoc wirelessnetwork, the wireless communications device comprising: a recordingportion that records country ID information indicating a country on theearth in to a storage medium, and that further records in to the storagemedium recording-time information indicating the time at which thecountry ID information was recorded in to the storage medium; a timedetermination portion that, at the start-up of the wirelesscommunication apparatus, determines whether a predetermined time periodhas elapsed from the time at which the country ID information wasrecorded in to the storage medium; and a channel setting portion that,when it is determined that the predetermined time period has not elapsedsince the country ID information was recorded in the storage medium,sets a wireless channel to a frequency channel that can be used in thecountry indicated by the country ID information that is recorded in thestorage medium.